Loftsson T, Konrádsdóttir F, Másson M
Faculty of Pharmacy, University of Iceland, Reykjavik, Iceland.
Pharmazie. 2006 Feb;61(2):83-9.
Most drugs permeate biological membranes via passive diffusion and it is generally assumed that the main barrier is the lipophilic structure of the membrane. However, we have observed that the unstirred water layer adjacent to the membrane surface can in some cases be a barrier just as effective as the lipophilic membrane itself. Hydrophilic cyclodextrins can enhance drug delivery through biological membranes by increasing the availability of dissolved drug molecules immediate to the membrane surface, i.e. by increasing drug delivery through the unstirred water layer. Cyclodextrins and drug/ cyclodextrin complexes are, in most cases, unable to permeate lipophilic membranes. Thus, excess cyclodextrin, more than is needed to solubilize the drug in the aqueous exterior, will hamper drug delivery through biological membranes.
大多数药物通过被动扩散穿透生物膜，通常认为主要屏障是膜的亲脂性结构。然而，我们观察到，与膜表面相邻的未搅动水层在某些情况下可能是与亲脂性膜本身一样有效的屏障。亲水性环糊精可以通过增加紧邻膜表面的溶解药物分子的可利用性来增强药物透过生物膜的传递，即通过增加药物透过未搅动水层的传递。在大多数情况下，环糊精和药物/环糊精复合物无法穿透亲脂性膜。因此，超过在水相外部溶解药物所需量的过量环糊精会阻碍药物透过生物膜的传递。
